Tuesday, January 14, 2014

Lack of Thyroid Hormone Doesn't Contribute to Cognitive Impairment, Study Finds

A new population study has failed to find a significant association between hypothyroidism and mild cognitive impairment, after accounting for possible confounding factors. The lead researcher was Ajay Parasaik, M.D., of the University of Texas and the Mayo Clinic. The results appear in JAMA Neurology.

Their findings, the researchers conclude, "suggest that neither clinical nor subclinical hypothyroidism is a risk factor for mild cognitive impairment...[and raise] questions about the need for routine testing of thyroid function as a part of the diagnostic workup in patients with mild cognitive impairment."

"This is a well-designed study of over 1,900 adults," Dilip Jeste, M.D., chair in aging at the University of California, San Diego, and a past APA president, told Psychiatric News. "After controlling for relevant variables, the investigators found no significant association between mild cognitive impairment (now labeled 'mild neurocognitive disorder' in DSM-5) and either clinical or subclinical hypothyroidism. The finding was notable as it comes from an outstanding and experienced group of researchers in the field, with the senior author—Ronald Petersen, M.D., Ph.D.—having served as co-chair of the DSM-5 Neurocognitive Disorders Work Group."

"The authors caution, however, that this was a cross-sectional study and that longitudinal replication of their finding is needed before  concluding that thyroid dysfunction is unrelated to mild neurocognitive disorder in older adults," Jeste said. "Also, the study did not evaluate people with dementia (major neurocognitive disorder). Therefore, although the study results are of considerable clinical value, they do not necessarily suggest abandoning thyroid function assessment in older adults at high risk for mild or major neurocognitive disorder."

More information on how patients should be evaluated for mild neurocognitive disorder or major neurocognitive disorder can be found in the Psychiatric News article, "New Guidance on Alzheimer's Spells Out Three Stages." Information on the subject can also be found in American Psychiatric Publishing's Clinical Manual of Alzheimer Disease and Other Dementias.

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